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High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators

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High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1881 High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators From module to system design approach LONG HOANG ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-513-0818-0 UPPSALA urn:nbn:se:uu:diva-397500 2019 Dissertation presented at Uppsala University to be publicly examined in Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Wednesday, 15 January 2020 at 09:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Professor Paul Tasker (School of Engineering, Cardiff University). Abstract Hoang, L. 2019. High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators. From module to system design approach. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1881. 98 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-0818-0. The rise of Big Science projects brings issues related to the energy consumption and the associated environmental impacts of such large-scale facilities. Therefore, environmentally- sustainable developments are undertaken towards the adoption of energy savings and improved energy-efficient approaches. The advent of the superconducting (SC) radio frequency (RF) accelerating cavity is bringing answers to these issues. Such superconducting RF (SRF) cavity is made of niobium that allows much higher accelerating gradients with a minimization of the energy consumption. The SC RF technology is increasingly used in many modern particle accelerators, including: the European Spallation Source (ESS), the X-ray Free Electron Laser (XFEL), the Linac Coherent Light Source (LCLS)-II and the proposed International Linear Collider (ILC). The innovation of solid state PA technology pushes limits regarding packaging, efficiency, frequency capability, thermal stability, making them more attractive than other well-established alternative technologies, such as vacuum tube technology in mid-range power applications. Through the investigations of designs and techniques, this research goal of the thesis allows to improve solid-state based power generation systems from module to the overall system design. This thesis introduces the single-ended PA design approach in planar technology and at kilowatt level. The design solution unlocks different possibilities including: improved integration, layout flexibility for tuning, and suitably for mass productions that are demanded in future high peak power generation systems. The novel amplifier design is followed by time domain characterization to fully evaluate the pulse profiles of such amplifiers when delivering kilowatt output power level for operation in conjunction with SRF accelerating cavities. Amplitude and phase stability of those amplifiers are also investigated in time-domain. The extracted data can then be used as measurement-based model for predicting factors which could degrade the overall stability of the associated PA. Future RF power generation systems built around solid state PAs need also efficient combining strategies. Two engineering design solutions are investigated in this thesis aiming for mid- and high- range power combination. One solution is based on a combination of the Gysel structure using suspended strip-line technology for improved power handling capability. Another solution is implementing a radial combiner, which uses re-entrant cavity resonator at 352 MHz and door-nob geometry for coupling at inputs and at the output. These solutions facilitate the scaling up 400 kW for powering ESS spoke cavities while maintaining a high degree of efficiency in RF power generation. This thesis gives insights of system integration and tuning procedures with a demonstration of combining 8 modules, delivering a total of 10 kW output power. Along with the proposed combining solutions at higher power levels, the nominal power block of 10 kW is used as an elementary block to propose scaling up in power till the 400 kW nominal power required by ESS. Finally, this thesis focuses on implementing an optimal charging scheme for SRF cavities, which helps reducing the wasted energy and improves the overall efficiency operation at future accelerating facilities. Therefore, these results contribute further to the larger adoption of solid state technologies in the future power generation systems for particle accelerators. Keywords: solid state technology, power amplifier, superconducting cavities, optimal charging, high efficiency, particle accelerators Long Hoang, Department of Engineering Sciences, Solid State Electronics, Box 534, Uppsala University, SE-75121 Uppsala, Sweden. Department of Physics and Astronomy, FREIA, Box 516, Uppsala University, SE-751 20 Uppsala, Sweden. © Long Hoang 2019 ISSN 1651-6214 ISBN 978-91-513-0818-0 urn:nbn:se:uu:diva-397500 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-397500) Dành cho bố mẹ, và vợ Dương Ngọc Hương Dedicated to my parents, and my wife Duong Ngoc Huong ”Move fast, and break things” Mark Zuckerberg List of papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Linus Haapala, Aleksander Eriksson, Long Hoang Duc and Dragos Dancila, "Kilowatt-level power amplifier in a single-ended architecture at 352 MHz," in Electronics Letters, vol. 52, no. 18, pp. 1552-1554, 2016. II Long Hoang Duc, Anirban Bhattacharyya, Vitaliy Goryasko, Roger Ruber, Anders Rydberg, Jorgen Olsson, and Dragos Dancila, "Time domain characterization of high power solid state amplifiers for the next generation linear accelerators," in Microwave and Optical Technology Letters, vol. 60, no. 1, pp. 163–171, 2018. III Long Hoang Duc, Anh Nguyen Dinh The, Duong Bach Gia, Magnus Jobs, Roger Ruber and Dragos Dancila, "High-power low-loss air-dielectric stripline Gysel divider/combiner for particle accelerator applications at 352 MHz," in The Journal of Engineering, vol. 2018, no. 5, pp. 264-267, 2018. IV Vitaliy Goryashko, Magnus Jobs, Long Hoang Duc, Johan Ericsson and Roger Ruber, "12-Way 100 kW Reentrant Cavity-Based Power Combiner With Doorknob Couplers," in IEEE Microwave and Wireless Components Letters, vol. 28, no. 2, pp. 111-113, Feb. 2018. V Long Hoang Duc, Magnus Jobs, Tor Lofnes, R. Ruber, Jorgen Olsson, and Dragos Dancila, "Feedback compensated 10 kW solid-state pulsed power amplifier at 352 MHz for particle accelerators," in Review of Scientific Instruments , vol. 90, no. 10, p. 104707, 2019. VI Long Hoang Duc, Tran Van Nghia, Arniban Bhattacharya, Tor Lofnes, Roger Ruber, Jorgen Olsson, and Dragos Dancila, "A Highly Efficient Solid State RF Power Source for Optimal Power Consumption during the Charging of Superconducting Cavities," Manuscript. Reprints were made with permission from the publishers. Other publications The following papers were not included in this thesis. VII Long Hoang Duc, Mans Holmberg, Adam Hjort, Roger Ruber, Anders Rydberg, and Dragos Dancila, "Monitoring of RF high power SSA with Arduino," in Swedish Microwave Days, March 15-16, Linkoping,¨ Sweden, 2016. VIII Long Hoang Duc, Anders Rydberg, Jorgen Olsson, Vitaliy Goryashko, Roger Ruber, and Dragos Dancila, "Time domain characterization of high power RF pulsed solid state amplifiers for linear accelerators," in Ninth CW and High Average Power RF Workshop, June 20-24, Grenoble, France, 2016. IX Dragos Dancila, Long Hoang Duc, Magnus Jobs, Mans Holmberg, Adam Hjort, Anders Rydberg, and Roger Ruber, "A compact 10 kW solid-state RF power amplifier at 352 MHz," in Journal of Physics: Conference Series, vol. 874, p. 012093, July 2017. X Stefan Book, Long Hoang Duc, Dragos Dancila, "Design, fabrication and measurement of 1 kW class-E amplifier at 100 MHz," in Swedish Microwave Days, May 24-25, Lund, Sweden, 2018. XI Long Hoang Duc, Anirban Bhattacharyya, Jorgen Olsson and Dragos Dancila, "Optimal Power Consumption during the Charging of Superconducting Cavities using Drain Voltage Modulation of Solid State Power Amplifiers," in Swedish Microwave Days, May 24-25, Lund, Sweden, 2018. XII Long Hoang Duc, Anirban Bhattacharyya, Jorgen Olsson and Dragos Dancila, "Implementation of a Highly Efficient Solid State RF Power Source for Superconducting Cavities," in Swedish Microwave Days, May 24-25, Lund, Sweden, 2018. Contents 1 Introduction 11 1.1 An overview of Microwave Power Generation Systems ..... 13 1.2 Solid state power amplifiers (SSPAs) for particle accelerators. 15 1.3 Thesis contributions and outline. ................ 19 2 Accelerators system 21 2.1 Particle Accelerators Basics ................... 21 2.1.1 The European Spallation Source (ESS) Linac ...... 23 2.1.2 Some basic definitions .................. 26 2.2 Review of power generation sources for particle accelerators . 29 2.2.1 Tetrode-based amplifiers ................. 29 2.2.2 Inductive output tube amplifiers ............. 30 2.2.3 Klystron amplifiers .................... 31 3 Results 33 3.1 High efficiency LDMOS-based power amplifiers ....... 34 3.1.1 Realization of single-ended design at kilowatt level . 34 3.2 High power time-domain characterization ............ 40 3.2.1 Measurement setup .................... 41 3.2.2 Simulation and measurement results discussion ..... 42 3.3 High power combiner approach ................. 46 3.3.1 Low and mid range power combining solution ..... 47 3.3.2 High power combiner .................. 49 3.4 Integration of solid-state high power generation for
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